RESUMEN
The Collum angle or the cephalometric crown-root angulation of permanent maxillary central incisors is an angle formed between the long axes of the crown and root of upper central incisors. This study aimed to evaluate the Collum angle in patients with Class II division 1 and 2 malocclusions for identifying the nature of differences, if any. Out of a total of 565 lateral cephalograms available at Lahore Medical and Dental College Orthodontic department during 2013-2014, 60 satisfied the inclusion criteria and 30 each were selected for the two malocclusion groups. The Collum angle of the permanent maxillary central incisors differ significantly among Class II division 1 and 2 permanent maxillary central incisor and showed pronounced axial bending in division 2 incisors [10.03° +/- 4.37°] as compared to division 1 [3.65° +/- 3.79°]. The mean difference between both groups was 6.38° + 5.81°. This feature could possibly contribute to the development of a deep overbite in Class II division 2 malocclusion and also may limit the amount of root torque during fixed appliance therapy